Per B31.3 Impact test exemption of weld metal below (continuation of closed thread292-509093)

[Santiago Vacca]

thread292-509093 closed, so I continue in this one.

When the MDMT is below -29°C lets say -40°C, and the welding consumable is classified by the applicable SFA below -29°C lets say E7018-1 -45°C.
for the base metal lets assume a stress ratio of 0.5 allows to reduce the MDMT of a curve B to -40°C.

[ul]
[li]wps is requiered to be impact tested because of Para. 323.2.2(h) allows welds stress ratio reduction to -29°C or,[/li]
[li]wps is not requiered to be impact tested because of Table 323.2.2 A-3 (b) allows welds to have its MDMT reduced to the SFA certified minimum lets say -45°C.[/li]
[/ul]


the following paragraphs of the B31.3 ed 2022 are:


Para. 323.2.2(h)
(h) For carbon, low alloy, and intermediate alloy steel
materials (including welds) that have not been qualified
by impact testing, the minimum temperature from
Table A-1, Table A-lM, or Figure 323.2.2A may be
reduced to a temperature no c o l d e r than -48 ° C
(-55 ° F) by the temperature reduction provided in
Figure 323.2.28 when (c) applies. For carbon, low
alloy, and intermediate alloy steel [highlight #FCE94F]welds[/highlight] that require
impact testing in accordance with Table 323.2.2, Box
A - 3 ( b ) , the temperature reduction from Figure
323.2.28 shall be applied to [highlight #FCE94F]-29° C[/highlight] (-20° F).

Table 323.2.2
A-3 (b) The weld metal of the
welding procedure qualification
test coupon shall be impact
tested at or below the design
minimum temperature when
that temperature is less than
-18° C (0° F), except when
Note (3) or Note (4) is satisfied;
testing of the weld metal
is not required when the clas-
sification of the welding
consumables according to the
filler metal specification
requires impact testing
below the design minimum
temperature.

 

[Maslov]

What is the question? It looks to me the situation is clear:

Desired MDMT of -40°C, Curve B material:

→ 323.2.2(c) Assuming (1) to (3) all apply: Allows reductions of Table 323.2.2B to be used​

→ 323.2.2(f) Requires impact testing below -29°C unless exempted by Table 323.2.2​

→ Table 323.2.2 Requires impact testing below -18°C, except when Note 3 or 4 are satisfied and the filler metal is qualified for the MDMT or lower.​

Following Note 3, follow 323.2.2(g) through (i). Only (h) has relevance to your situation:

→ 323.2.2(h) States minimum temp may be reduced to a temp no colder than -48°C, and if Table 323.2.2 requires impact testing then your Table 323.2.2B reduction shall be applied to -29°C​

Note 3 is satisfied, as 323.2.2(h) is satisfied (-40°C MDMT > -48°C). So, if using a -45°C filler metal, Table 323.2.2 does not require impact testing. Thus, 323.2.2(f) is exempted, no impact testing is required.


It looks like you may have misread 323.2.2(h). It is not saying you can only reduce down to -29°C, it is saying you must apply your reduction to -29°C if impact testing is required by the table (which it is not, so the number is not even relevant). Regardless, assuming a thickness at or below 10mm and a 0.5 stress ratio (reduction is 34°C):

-29°C - 34°C = -63°C (Which gets limited to -48°C by 323.2.2(h))​

Like WE91 said on the previous post, keep life simple, use an impact tested material (eg. A333 Gr6) and a low-temp electrode. Cost differences tend to be negligible and it keeps observers happy. Using a "regular" temp material at lower temps tends to raise eybrows.

 

[Santiago Vacca]

Thank you Maslov and WE91.

My interpretation of Para. 323.2.2(h) is that "base materials, inc. a welded tee for example" can go down to -48°C for stress ratios reduction, and "welds" can go down to -29°C for stress ratio reduction. Furthermore Box A - 3 ( b ) requires that under -18°C the consumable has to be impact tested under the MDMT by its SFA.

Example1:

SR=1
base metal A106B curve B -29°C

if consumable ER70s3 imp cert. to -20°C
For MDMT down to -20°C wps w/o impact, between -20 and -29°C wps w/ impact. under -29°C impact to base metal too.

if consumable ER70s6 imp. cert, to -30°C.
For MDMT down to -29°C wps w/o impact, between -29 and -30°C wps w/ impact. under -30°C impact to base metal too.


Example2:

SR=0.5
base metal A106B curve B -29°C + SR = -48°C

if consumable ER70s3 imp cert. to -20°C
For MDMT down to -20°C wps w/o impact, between -20 and -29°C wps w/ impact. under -48°C impact to base metal too.

if consumable ER70s6 imp. cert, to -30°C.
For MDMT down to -29°C wps w/o impact, between -29 and -30°C wps w/ impact. under -48°C impact to base metal too.

if consumable E7018-1 imp. cert, to -45°C.
For MDMT down to -29°C wps w/o impact, between -29 and -45°C wps w/ impact. under -45°C to -48°C wps w/ impact. under -48°C impact to base metal too.

Example3:

SR=0.25
no impact requirements to base metal and wps w/o impact down to -104°C, by 323.2.2(g).


With the above I see consistency between B31.3 and B31T.


My conclusion is that:
[ul]
[li]for a non-impacted base metal I can go down to -18°C just by being above its curve on Figure 323.2.2A[/li]
[li]below -18 and down to -29°C I can use wps w/o impact if consumable is certified by SFA below -29°C[/li]
[li]between -29 and -48°C wps w/ impact, base metal can be impact exempted by the SR reduction of Figure 323.2.2B[/li]
[li]under -48 down to -104°C only possibility is to have a SR below 0.3, in this case no impact for base metal and wps w/o impacts.[/li]
[/ul]